Adam Hayes, Ph.D., CFA, is a financial writer with 15+ years Wall Street experience as a derivatives trader. Besides his extensive derivative trading expertise, Adam is an expert in economics and ...

Investopedia contributors come from a range of backgrounds, and over 25 years there have been thousands of expert writers and editors who have contributed. Erika Rasure is globally-recognized as a ...

Obesity is a condition in which excess fat has accumulated in the body, such that it can have an adverse effect on health. Obesity is defined as a body mass index (BMI) of greater than 30 kg/m2.